Concentrated Vanilla

Tinker's Construct(and several addons, like Constructs Armory) for ore/tool rework
Minecraft Comes Alive for Village reworks

Better Combat Rebirth (and several other HUD mods) for a combat/ui rework

Pam's Harvestcraft & Rustic for food/drink rework (in conjunction with Tough As Nails!)

YUNG's Better Caves/Mineshafts, NetherEx and for world generation rework

in combination with Chunk-Pregenerator for smooth generation

Animania Farm & Extra for animals rework

Several of Macaw's & MrCrayfish's building/furniture for some more decoration
Primitive Mobs for adding some vanilla friendly mobs

Bountiful to add some vanilla friendly goals

Serene Seasons (in conjunction with some "pretty" mods) for a dynamic world feel

and tons of quality of life and performance mods!